Poly(ADP-ribose) polymerase forms loops with DNA

The interaction between highly purified poly(ADP-ribose) polymerase from calf thymus and different topological forms of pBR322 DNA has been studied by gel retardation electrophoresis and electron microscopy. We show that: (i) in the absence of nicks on DNA the enzyme has a marked affinity for supercoiled (form I) DNA, (ii) in the presence of single stranded breaks poly(ADP-ribose) polymerase preferentially binds to form II, (iii) in all cases enzyme molecules are frequently located at DNA intersections, (iv) a cooperative binding of the enzyme on DNA occurs.     

Investigation of fullerenol-induced changes in poroelasticity of human hepatocellular carcinoma by AFM-based creep tests

In this study, atomic force microscopy (AFM) is used to investigate the alterations of the poroelastic properties of hepatocellular carcinoma (SMMC-7721) cells treated with fullerenol. The SMMC-7721 cells were subject to AFM-based creep tests, and a corresponding poroelastic indentation model was used to determine the poroelastic parameters by curve fitting. Comparative analyses indicated that the both permeability and diffusion of fullerenol-treated cells increased significantly while their elastic modulus decreased by a small amount. From the change in the trend of the determined parameter, we verified the corresponding alternations of cytoskeleton (mainly filaments actin), which was reported by the previous study using confocal imaging method. Our investigation on SMMC-7721 cell reveals that the poroelastic properties could provide a better understanding how the cancer cells are affected by fullerenol or potentially other drugs which could find possible applications in drug efficacy test, cancer diagnosis and secure therapies.     

Poly(ADP-ribose)polymerase: a novel finger protein.

By Energy Dispersive X-ray fluorescence we have determined that calf thymus poly(ADP-ribose) polymerase binds two zinc ions per enzyme molecule. Using 65Zn (II) for detection of zinc binding proteins and polypeptides on western blots, we found that the zinc binding sites are localized in a 29 kd N-terminal fragment which is included in the DNA binding domain. Metal depletion and restoration experiments proved that zinc is essential for the binding of this fragment to DNA as tested by Southwestern assay. These results correlate with the existence of two putative zinc finger motifs present in the N-terminal part of the human enzyme. Poly(ADP-ribose)polymerase fingers could be involved in the recognition of DNA strand breaks and therefore in enzyme activation.     

Survey of the mycoflora and mycotoxins of cotton seeds and cotton seed products in Egypt

Thirty-nine species and 16 fungal genera were isolated from Egyptian cotton seeds, cotton seed meal and cotton seed cake on 1% glucose-Czapek's agar medium incubated at 28 °C. Aspergillus was the most frequent genus and it emerged in 87–100% of the samples contributing 70–98% of total fungi in the three substrates tested. The most common species were A. niger, A. flavus, A. fumigatus, A. terreus and Rhizopus stolonifer; A. niger, A. fumigatus and Penicillium corylophilum; and A. niger, A. flavus, A. terreus, A. nidulans and Rhizopus stolonifer, respectively. Cotton seeds and cotton seed products were naturally contaminated by aflatoxin B₁ and B₂. About 16% of the different substrates tested were positive for aflatoxin contamination. No citrinin, ochratoxin A, patulin, sterigmatocystin, diacetoxyscirpenol, T-2 toxin or zearalenone were detected in the samples assayed.     

Dot-enzyme-linked immunosorbent assay (dot-ELISA) for the rapid diagnosis of human fascioliasis

A dot-enzyme-linked immunosorbent assay (dot-ELISA) was developed as a fast and field applicable antibody detection tool for the diagnosis of human fascioliasis. The assay is performed using partially purified antigens from a species of Fasciola at 180 ng protein/dot (2 microliters) and serum samples at 1:20 dilution (1 microliter). Dot-ELISA results completely agreed with those of micro-ELISA. Antigen-coated nitrocellulose sheets stored for 3 mo at -20 C showed results identical to fresh sheets. Sera from patients with fascioliasis (n = 30) and other parasitic or viral infections (n = 120) were compared with sera from healthy controls (n = 14). Ninety samples can be tested within 90 min. The sensitivity, specificity, and speed of the assay may justify its use in laboratory and field studies.     

Mutations in argininosuccinate synthetase mRNA of Japanese patients,causing classical citrullinemia.

Citrullinemia is an autosomal recessive disease caused by a genetic deficiency of argininosuccinate synthetase. In order to characterize mutations in Japanese patients with classical citrullinemia, RNA isolated from 10 unrelated patients was reverse-transcribed, and cDNA amplified by PCR was cloned and sequenced. The 10 mutations identified included 6 missense mutations (A118T, A192V, R272C, G280R, R304W, and R363L), 2 mutations associated with an absence of an exon 7 or exon 13, 1 mutation with a deletion of the first 7 bp in exon 16 (which might be caused by abnormal splicing), and 1 mutation with an insertion of 37 bp within exons 15 and 16 in cDNA. The insertion mutation and the five missense mutations (R304W being excluded) are new mutations described in the present paper. These are in addition to 14 mutations (9 missense mutations, 4 mutations associated with an absence of an exon in mRNA, and 1 splicing mutation) that we identified previously in mainly American patients with neonatal citrullinemia. Two of these 20 mutations, a deletion of exon 13 sequence and a 7-bp deletion in exon 16, were common to Japanese and American populations from different ethnic backgrounds; however, other mutations were unique to each population. Furthermore, the presence of a frequent mutation--the exon 7 deletion mutation in mRNA, which accounts for 10 of 23 affected alleles--was demonstrated in Japanese citrullinemia. This differs from the situation in the United States, where there was far greater heterogeneity of mutations.     

Use of histone antibodies for studying chromatin topography and the phosphorylation of chromatin subunits

Polyclonal and monoclonal antibodies specific for histones as well as sera directed against synthetic peptides of histones were used to probe the topography of chromatin subunits. In native chromatin, the regions corresponding to residues 130-135 of H3 and 6-18 of H2B were found to be exposed and able to interact with antibodies whereas the regions 26-35 and 36-43 of H2B and 80-89 and 85-102 of H4 were not. In vitro phosphorylation of H3 and H5 in native chromatin or of H3 in H1/H5-depleted chromatin led to a marked drop in the binding of antibodies specific for residues 130-135 of H3 and 6-18 of H2B. Phosphorylation of H1/H5-depleted chromatin also altered the degree of exposure of certain H2A epitopes but it did not affect the surface accessibility of residues 1-11 of H2B.     

Relation of birth weight and childhood respiratory infection to adult lung function and death from chronic obstructive airways disease.

OBJECTIVE--To examine whether birth weight, infant weight, and childhood respiratory infection are associated with adult lung function and death from chronic obstructive airways disease. DESIGN--Follow up study of men born during 1911-30 whose birth weights, weights at 1 year, and childhood illnesses were recorded at the time by health visitors. SETTING--Hertfordshire, England. SUBJECTS--5718 men born in the county during 1911-30 and a subgroup of 825 men born in the county during 1920-30 and still living there. MAIN OUTCOME MEASURES--Death from chronic obstructive airways disease, mean forced expiratory volume in one second (FEV1) and forced vital capacity (FVC), and respiratory symptoms. RESULTS--55 men died of chronic obstructive airways disease. Death rates fell with increasing birth weight and weight at 1 year. Mean FEV1 at age 59 to 70 years, adjusted for height and age, rose by 0.06 litre (95% confidence interval 0.02 to 0.09) with each pound (450 g) increase in birth weight, independently of smoking habit and social class. Bronchitis or pneumonia in infancy was associated with a 0.17 litre (0.02 to 0.32) reduction in adult FEV1 and with an increased odds ratio of wheezing and persistent sputum production in adult life independently of birth weight, smoking habit, and social class. Whooping cough in infancy was associated with a 0.22 litre (0.02 to 0.42) reduction in adult FEV1. CONCLUSIONS--Lower birth weight was associated with worse adult lung function. Intrauterine influences which retard fetal weight gain may irrecoverably constrain the growth of the airways. Bronchitis, pneumonia, or whooping cough in infancy further reduced adult lung function. They also retarded infant weight gain. Consistent with this, death from chronic obstructive airways disease in adult life was associated with lower birth weight and weight at 1 year. Promoting lung growth in fetuses and infants and reducing the incidence of lower respiratory tract infection in infancy may reduce the incidence of chronic obstructive airways disease in the next generation.     

Growth and Physiology of Maize (Zea mays L.) in a Nickel-Contaminated Soil and Phytoremediation Efficiency Using EDTA

Journal of Plant Growth Regulation - Nickel (Ni) element is strongly phytotoxic at high concentrations for several plants, but due to its dual behavior and complicated chemistry, it has received...